This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Children's productive vocabularies suggest that object labels (nouns;e.g. truck) are easier to learn than action labels (verbs;e.g., jump). Are verbs also more difficult to comprehend? Study 1 examines children's comprehension of nouns versus verbs at 14, 16, and 18 months using a vocabulary checklist completed by parents and the Preferential Looking Task (PLT). For the PLT, 32 children at each age are randomly assigned to the noun versus verb condition. Children view two objects or two actions before (baseline trial) and after (test trial) one of the objects or actions is labeled. Comprehension is defined as an increase in looking at the labeled image during the test trial compared to baseline. We predict that at each age (1) children will comprehend verbs and nouns, and (2) parent report will more accurately reflect children's comprehension of nouns than verbs. Study 2 examines children's ability to learn a new verb at 14, 16, and 18 months. Children are shown a novel action that is labeled with a novel verb;a second action is presented but not labeled. 32 children at each age are randomly assigned to hear 3 versus 7 repetitions of the novel verb. The PLT is used to assess comprehension of the novel verb. We predict: (1) at each age, children will comprehend the novel verb, (2) at 14 and 16 months, comprehension will be successful at 7 but not 3 repetitions, and (3) at 18 months, comprehension will be successful at both 3 and 7 repetitions.